1. Field of the Invention
The present invention relates to pressure sensors installed in small electronic devices, such as cellular phones. In particular, the present invention relates to a pressure sensor capable of changing a resolution of a switch signal from a switch in accordance with the amount of a pressing force applied on an operating surface.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 2001-142615 discloses a remote control transmitter, which is exemplarily shown in FIG. 1 of this patent document. This patent document describes, in particular, processing when a plurality of buttons is depressed. One such processing is that the center button is regarded as being depressed when a plurality of buttons is depressed and the number of depressed buttons is an odd number.
As shown in FIG. 11, in a device having five buttons A to E in all, when the button A to the button E is depressed in succession, a switch signal (digital signal) is output from each depressed button, and the depressed button is switched on.
Conventionally, however, it is determined merely whether each button is in the on state or off state from a switch signal from each button, as shown in FIG. 11. Therefore, even if the amount of a pressing force applied on the button is changed, an output waveform is the same as shown in FIG. 11. In other words, since an ON signal is simply output, a pressure sensor disclosed in Japanese Unexamined Patent Application Publication No. 2001-142615 cannot realize various functions.